Voltage-limiting arc interrupter



Jan. 6, 1948. R. R. PITTMAN 2,434,010

VOLTAGE-LIMITING ARC INTERRPTER Filed Jan. 19, 1945 F-l'g. l m25 Fl'g-2 m25 l VENToR l W Patente'cl Jan. 6, 1948 UNITED `STATES PATENT OFFICE 2,434,010 "vL'rAGE-'Lmrrmo Ro-ITRRUPR Balpen; "Pittman, Park nin, Ark. .Appiia'tin January' 19, 1945, serial No. 573,572

(Chiva-30') -'5'*c1aims.

This invention4 relatesgenerally to lightning y"pritective devices yoff'a` character adapted` 'for use with.energizedelectrical circuits'f'or the pur- 'pose of limiting the voltage rise of an associated conductor' by discharging abnormal `or superimposedenergy and 'interrupting the passage of energy when normal conditions are restored;

t The present invention is an improvement on the construction described in Patent No. 2,164,720, vissued to Ralph R. Pittman, and dated July 4, '1939.

Among'theobjects'of the presentinvention may be noted: (d) the provisioniin aV tubeiller, arcjel'orilgating device ofthe character ldescribed 'of means (for supporting'the l'ler such that the 'exhaust gases react to hold thefller inthe desired initial position; (b) the'provisionof an improved arrangement vfor combining the ller with the terminal members of the device; k('c) the provision of va construction having venting characteristics -favorable for arc-elongation and (d) the provision of a simple, eiiicient and inexpensive struc'- ture in which more than one function is performed by each of several individual elements.

With these and other objects'in view which will appear from the description, my invention resides in lthe novel `form, combination and construction of the parts of the device,and the scope of the invention will'bei'ndicated by the'appended claims.

The drawing illustrates to actual scale van yernbodiment of the invention suitable foralternatingV current circuits operating'up -to 9 kv. lR'. M. S, Fig. 1 is an elevational'view oi the device, shown partly in section; Fig. 2 illustrates in elevation the external appearance of the devicetFig. 3 is a view of the lower endof the device; Fig. 4' is a section along the line 4-'-4 of Fig. 2.

In the embodiment 'of the invention illustrated, an upwardly extending tube I3, of insulating material, e. g. hard Yliber, is open at its lower end, andthe upper end is internally threaded toreceivfe thethreadedguide sleeve 22. Afg'uide block!! 8 'isad'apted for reciprocable vertical movement in vtheY lower end of the sleeve 22, and the terminal bolt'2'3 threadedly engages'an upper portion 4of the 'sleeve 22', extending upwardly above the 'upper end ofthe tube I3. A springZI is in-v terposed between'th'e" upper end of thefguide-b-lock la'and the 'lower end -of the terminal bolt 23, and 'continuously' urges the guide r'blo/ck 8 'downwardly. The sleeve 22', "the guide block I8, the terminal bolt 23 and the spring 2| constitute a conducting assembly 'which closes tube I3 at its upper end.V

the bore vof 'theV Near 'and 'somewhat above j the lower end "of the tube I3, lthe' lower terminal bolt I 'I je'xtenfds transversely therethrough. lThe diameter of that portion of thebolt l`I"I within the bore of the'tbe I3 is smaller than the bore, so that a laterally extending space is provided at 'each side ofthe bolt II within the tube I3; y,

A cylindrical ller 'III, ,of insulating material, extends longitudinally within and partially closes the bore of the tube I?, betweenthe terminal'bolt I"I and the vguidefblo ck I8, The respective ends I'Sand 2 0 of the ller III are'cut'vso that thefend surfaces lie in intersecting planes, 'similart'o portions cffthe sloping surfaces of'a wedge, andthe downwardly-biasedguide blockl 8 cooperates with the terminal I 'I through the respective sloped yends ofthe iiller 'I4 to urge thelatter laterally to longitudinal abutment with theinner surface ofj the tube I3. Aconductingmember I6 embraces the lower end of the filler |4` in contact with the terminal member I'I, andextends upwardly along the line of abutment of the latter with the tube I3 toward and in spaced relationship with 'the guide block I8.

A flanged sleeve I2 is fitted over the lower end 'of the tube I3 and 4fastened in place by the extension of the terminal bolt Il therethrough, and a cover I I, between the nut 2'4 and the uDDr end of 'the guidefsleeve 22, extends outwardly beyond the tube"I3. A housing I0, of insulating material, for example, porcelain or glass, encloses that portion of the device between the cover Il and the upper end vof the flanged sleeve I2. If desired, kthe wall Strength'of the tubeY I3 may be reinforced by pressing thereon a 'steel sleeve I5, externally of the tube and betweenthe guide block I8 and the conducting member I6.

While various mounting arrangements ma-ybe used as desired, the device is here shown so uthat the upper terminal 23 is vspaced from the con# ductor 25 by the air gap`26 for the purpose of limiting the voltage v.rise of the conductor. The device is supported from the lower vend by means of the mounting bracket 2,8 (partially shown), which is clamped between the lower terminalnts 21 and 29.

To assure proper operation, the device should be constructed so that the weakest electrical 'path through the device includes the g'ap adjacent to the lin'e of 'abutment between the upper end 'of the initiating electrode 'It 'andthe lower end of the upper conducting closure, however the latter may be constructed. Following initial s'1`: fai.k over along the line of abutment, any ensuingarc is quickly moved 'along With the evolved gast'- ward the path of least restriction, which in the device illustrated is opposite the line of abutment. In so doing, the arc is cooled to extinguishment. This phenomenon of arc elongation is more fully described in the above-mentioned Patent No. 2,164,720.

As the accompanying drawing shows to actual size, the length of the initial are path is 1%, the length of the nal arc path (path of least restriction) is 2, the bore of the tube is 3A, and the diameter of the ller is l-, In its movement around the filler, the arc moves peripherally between and over about one inch of ber surfaces, which movement cools the arc sufficiently to render the device inherently current-limiting within the voltage gradients existing on 9 kv. R. M S. 60 cycle circuits.

Gas evolved during operation is discharged through the open end of the device, moving downwardly along the ller I4, and tending to expel the ller from the tube. Advantage is taken of this fact by sloping the lower end of the filler I4 at its contact with the terminal l1 so that its lower end is driven by gas discharge tightly against the line of abutment, thus not only providing maximum shielding of the initiating electrode I6, but also assuring high pressure contact of the initiating electrode with the terminal member when these elements are carrying current.

For best operation, it is desired that nothing move in the device except the arc. The resilient guide-block construction here shown is not necessary for this type of operation, but is desirable to compensate for the change in dimensions of the ber parts which accompanies change in humidity. Hard fiber is the best material I have so far discovered for the tube and filler, but should some nonhygroscopic material having other suitable physical characteristics be used, the conducting closure holding the upper end of the filler in place may be of rigid construction.

While only one embodiment of the invention has been herein described in detail, it will be apparent that the construction shown may be readily modified by simple dimensional changes to adapt the device for use with circuit voltages other than the 9 kv. previously mentioned. It is intended that the drawing and description of the invention here presented will be regarded as generally illustrative, rather than specically limiting.

I claim, as my invention:

1. A voltage-limiting arc interrupter comprising a. tube of insulating material open at the lower end thereof, a closure of conducting material at the upper end thereof, a cylindrical filler of insulating material partially closing the bore of said tube and positioned in lateral abutting engagement with the inner surface thereof, said filler being so formed that the upper end surface of said filler slopes downwardly from the line of abutment of said ller with said tube and the lower end surface of said iiller slopes upwardly from said line of abutment, means cooperating with said ller and engaged with the respective end surfaces for holding said filler in lateral abutting engagement with said tube, said last-named meansr including a conducting member extending endwise into said tube to engagement with the upper sloped surface f said ller and a conducting terminal member extending transversely across and in engagement with the lower sloped surface of said ller, and structural means for causing sparkover to occur along said line of abutment, said structural means including a conducting member extending upwardly along a por- 4 tion of said line of abutment and in spaced relationship with said conducting closure.

2. A voltage-limiting arc interrupter comprising a tube of insulating material open at its lower end, a terminal member having a diameter less than the bore of said tube extending diametrically across the bore of said tube near the lower end thereof, a ller carried by said terminal member within said tube, said ller partially closing the bore of said tube and having the respective ends thereof sloped so that the end surfaces lie in intersecting planes, conducting means closing the upper end of said tube, said conducting means including a longitudinally extending conducting member in endwise engagement with the upper sloped surface of said filler cooperating with said terminal member in engagement with the lower sloped surface of said filler for holding the ller in longitudinal abutment with said tube, and structural means for causing sparkover to occur adjacent to the line of abutment of said filler with said tube, said structural means including a conducting member extending upwardly along a portion of said line of abutment and in spaced relationship with said conducting means.

3. A voltage-limiting arc interrupter comprising a tube of insulating material open at its lower end, a terminal member having a diameter less than the bore of said tube extending diametrically across the bore of said tube near the lower end thereof, a ller carried by said terminal member within said tube, said ller partially closing the bore of said tube and having the respective ends thereof sloped so that the end surfaces lie in intersecting planes, a guide sleeve of conducting material tted into the upper end of said tube, a reciprocably movable guide block extending upwardly into said guide sleeve, resilient means concurrently urging said guide block to engagement with the upper sloped surface of said filler and the lower sloped surface of said ller against said terminal member whereby said filler is urged laterally along a line of abutment against the inside of said tube, and structural means for causing sparkover to occur adjacent to said line of abutment, said structural means including a conducting member extending upwardly along a portion of said line of abutment and in spaced relationship with said guide sleeve.

4. A voltage-limiting arc interrupter comprising a tube of insulating material, a longitudinally extending ller of insulating material having a diameter less than the diameter of said tube positioned within said tube in lateral abutting relation along a line of abutment with the inner surface of said tube, said filler having an upper end surface sloping downwardly and outwardly from said line of abutment and a lower end surface sloping upwardly and outwardly from said line of abutment, a terminal member supporting said ller, said terminal member having a diameter less than the diameter of said ller and extending transversely across the lower sloped end of said nller, a conducting member extending coaxially within said tube in engagement with the upper sloped end of said filler, and structural means for causing sparkover between said conducting member and said terminal member to occur along said line of abutment, said means including an electrode resting on said terminal member and extending across the lower surface of said ller in a direction normal to the axis of said terminal member toward said line of abutment and thence upwardly therealong in spaced relationship with said conducting member.

5. A voltage-limiting arc interrupter comprising a tube of insulating material, a longitudinally extending iiller of insulating material having a diameter less than tlie diameter of said tube positioned within said tube in lateral abutting relation along a line of abutment with the inner surface of said tube, said filler having an upper end surface sloping downwardly and outwardly from said line of abutment and a lower end surface sloping upwardly and outwardly from said line of abutment, a conducting terminal member supporting said filler, said terminal member extending horizontally across the lower sloped end of said filler, a conducting member supported from the upper end of said tube and extending longitudinally within said tube in engagement with the upper sloped end of said iiller, said conduct ing member being resiliently pressed in endwise direction for wedging said filler from its respective sloped ends against said tube along said line of abutment, and structural means for causing sparkover between said conducting member and said terminal member to occur along said line of abutment, said structural means including an electrode of conducting material resting on said terminal member and extending across the lower surface of said ller in a direction normal to the axis of said terminal member to said line of abutment and thence upwardly7 therealong in spaced relationship with said conducting member.

RALPH R. PITTMAN.

CIITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,002,042 Pittman May 21, 1935 2,164,720 Pittman July 4, 1939 2,169,110 Pittman Aug. 8, 1938 2,338,479 Ackermann Jan. 4, 1944 

